BACKGROUND
[0001] For some applications, it is desirable to plasma treat a container. For example,
plasma treatment is useful for medicinal inhalation devices, including pressurized
inhalers such as metered dose pressurized inhalers (MDIs) and dry powder inhalers
(DPIs), which are widely used for delivering medicaments. The relatively high surface
energy of materials typically used as containers for medicinal inhalation devices
(e.g., deep drawn stainless steels or aluminum) can cause medicament particles in
suspension formulations, for example, to adhere irreversibly to or adsorb onto the
interior surface of the container. Such adhesion or adsorption can lead to a loss
of potency and/or erratic dosing during the shelf-life of the device. Interaction
between a container and a medicinal formulation can also potentially lead to enhanced
medicament degradation or corrosion of the container.
[0002] While plasma treatment methods are known for modifying the surface properties of
various articles, plasma treatment of containers continues to provide challenges.
[0003] WO2009/036579 discloses an apparatus for plasma treating multiple containers, the apparatus comprising
a manifold with multiple outlet openings, multiple nozzles connected to the multiple
outlet openings protruding from the manifold and interconnected pathways for connecting
the nozzles to a supply of plasma-generating gas or a vacuum source.
SUMMARY
[0004] The present disclosure provides an apparatus and a method for plasma treatment of
multiple containers. The apparatus and method disclosed herein utilize hollow, electrically-conductive
nozzles, which serve as both at least partial electrodes (e.g., grounded electrodes)
for plasma treatment and at least one of inlets or outlets for plasma-generating gas.
During plasma treatment the nozzles extend into the containers to be treated, and,
in some embodiments, the containers also serve as electrodes (e.g., radio frequency
powered electrodes). In the apparatus and method disclosed herein, introducing or
exhausting gas through the hollow electrodes favorably allows for uniformity of the
treatment on the interior of a container, while the multiple hollow electrodes in
the apparatus allow for multiple container interiors to be treated at the same time.
The ability to treat multiple container interiors is more cost effective and requires
shorter processing times than apparatuses and methods that 1) require an entire container
(inside and outside) to be treated and/or 2) allow for treatment of only a single
container at a time.
[0005] In one aspect, the present disclosure provides an apparatus for plasma treating multiple
containers according to claim 1.
[0006] In another aspect, the present disclosure provides a method of plasma treating multiple
electrically-conductive containers according to claim 12.
[0007] In the foregoing aspects, the apparatus is typically part of a capacitively coupled
reactor system. In some embodiments of the foregoing aspects, the manifold further
comprises a second chamber adjacent the first chamber, the second chamber comprising
multiple passages therethrough aligned with the multiple outlet openings, wherein
the multiple hollow, electrically-conductive nozzles extend through the multiple passages.
In some embodiments, the multiple hollow, electrically-conductive nozzles extend through
the multiple passages without sealing off the passages entirely. In these embodiments,
each of the multiple passages in the second chamber includes a space (e.g., an unsealed
space or physical gap) surrounding one of the hollow, electrically-conductive nozzles.
In other embodiments, the multiple passages in the second chamber comprise sealing
connections to the multiple hollow, electrically-conductive nozzles. In these embodiments,
wherein the multiple passages in the second chamber are sealed off by the nozzles,
typically a middle portion of each hollow, electrically-conductive nozzle has a central
bore and at least two outer bores substantially parallel to the central bore, wherein
the at least two outer bores tap into the second chamber. In some embodiments, the
first chamber is connected to a gas supply, and the second chamber is connected to
a vacuum source. In other embodiments, the first chamber is connected to a vacuum
source, and the second chamber is connected to a gas supply.
[0008] We have found that plasma deposition methods and apparatuses that are configured
to treat an entire container (inside and outside) tend to provide in some circumstances
an undesirable number of containers that leak. The leakage is presumably due to a
thick coating that can form on the brim of the container. The apparatus and method
disclosed herein are configured to treat primarily an interior surface (i.e., at least
a portion of the interior) of a container, eliminating the problem of excess coating
on the brim. Advantageously, for at least some embodiments of the disclosure, plasma
coatings can be deposited uniformly on the interior of a container. Uniform coating
is facilitated by the coaxial electrode and gas inlet and/or outlet provided by the
hollow, electrically-conductive nozzles and, in at least some embodiments, the central
disposition of these nozzles inside the containers during treatment. Furthermore,
in at least some embodiments, the present disclosure advantageously provides for uniform
coating among multiple containers that are treated simultaneously. To favorably affect
the coating uniformity among multiple containers, some embodiments of the present
disclosure provide at least one of substantially uniform pressure among multiple containers,
substantially equal gas flow paths into the containers, or substantially equal flow
paths for exhausting gas from the containers.
[0009] In this application, terms such as "a", "an" and "the" are not intended to refer
to only a singular entity, but include the general class of which a specific example
may be used for illustration. The terms "a", "an", and "the" are used interchangeably
with the term "at least one". The phrases "at least one of" and "comprises at least
one of" followed by a list refers to any one of the items in the list and any combination
of two or more items in the list. All numerical ranges are inclusive of their endpoints
and non-integral values between the endpoints unless otherwise stated.
[0010] The terms "first" and "second" are used in this disclosure. It will be understood
that, unless otherwise noted, those terms are used in their relative sense only. In
particular, in some embodiments certain components may be present in interchangeable
and/or identical multiples (e.g., pairs). For these components, the designation of
"first" and "second" may be applied to the components merely as a matter of convenience
in the description of one or more of the embodiments.
[0011] The term "plasma treatment" as used herein includes plasma etching, plasma priming,
plasma deposition, and plasma polymerization. The apparatus and method disclosed herein
are useful for each of these plasma processes. The term "plasma treatment" as used
herein typically refers to plasma treatment carried out under conditions of ion bombardment.
[0012] The term "multiple" as used herein refers to more than one. Therefore, the apparatus
disclosed herein includes at least two hollow, electrically-conductive nozzles (and
corresponding outlet openings in the first chamber). The number of nozzles and corresponding
outlet openings in the apparatus may be selected based on the size and design of the
apparatus. In some embodiments, the apparatus includes up to 2500, or in some embodiments,
any number between 2 and 2500 nozzles (and corresponding outlet openings in the first
chamber) to plasma treat a corresponding number of containers. For example, the apparatus
may include 2, 4, 8, 16, 32, 64, 128, 256, 512, or 1024 nozzles and corresponding
outlet openings.
[0013] The above summary of the present disclosure is not intended to describe each disclosed
embodiment or every implementation of the present disclosure. The description that
follows more particularly exemplifies illustrative embodiments. It is to be understood,
therefore, that the drawings and following description are for illustration purposes
only and should not be read in a manner that would unduly limit the scope of this
disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The disclosure may be more completely understood in consideration of the following
detailed description of various embodiments of the disclosure in connection with the
accompanying drawings, in which:
FIG. 1A is a perspective view of an exemplary embodiment of an apparatus according
to the present disclosure;
FIG. 1B is a perspective view of the opposite face of the exemplary embodiment shown
in FIG. 1A;
FIG. 2 is a perspective view of a hollow, electrically-conductive nozzle useful in
some embodiments of an apparatus according to the present disclosure;
FIG. 3A is a perspective view of an exemplary embodiment of a second chamber component
useful in some embodiments of an apparatus according to the present disclosure;
FIG. 3B is a perspective view of the opposite face of the exemplary embodiment shown
in FIG. 3A;
FIG. 4 is an exploded perspective view of an exemplary embodiment of an apparatus
according to the present disclosure;
FIG. 5 is a plan view of optional, interior cooling channels included in the exemplary
embodiment shown in FIGS. 1A and 1B;
FIG. 6 is a partial cross-sectional side view of another exemplary apparatus according
to the present disclosure;
FIG. 7 is a perspective view of a hollow, electrically-conductive nozzle useful for
the apparatus shown in FIG. 6; and
FIG. 8 is a perspective view of another exemplary apparatus according to the present
disclosure.
DETAILED DESCRIPTION
[0015] Reference will now be made in detail to embodiments of the disclosure, one or more
examples of which are illustrated in the drawings. Features illustrated or described
as part of one embodiment can be used with other embodiments to yield still a third
embodiment. It is intended that the present disclosure include these and other modifications
and variations.
[0016] An apparatus 9 for plasma treating multiple containers is shown in FIGS. 1A and 1B.
Apparatus 9 can be useful, for example, as a component of apparatus 90 shown in FIG.
4. In the illustrated embodiment, manifold 2 comprises a first plate 1 having a first
face 11 and a second face 12. Multiple hollow, electrically-conductive nozzles 10
are connected to multiple outlet openings (not shown) in the first plate 1 and protrude
from the second face 12 of the first plate 1. For example, the nozzles 10 may be press
fit into the outlet openings in the first plate, or they may be sealed into the outlet
openings (e.g., using o-rings). The first chamber in manifold 2 comprises a first
plurality of pathways 14 in the first face 11 of the first plate 1 for connecting
the multiple hollow, electrically-conductive nozzles 10 to a supply of plasma-generating
gas or a vacuum source (not shown). The first plate 1 illustrated in FIG. 1B also
includes port 18 extending therethrough. Port 18 is adapted to connect to a supply
of plasma-generating gas or a vacuum source (not shown). The first plate 1 can therefore
be useful in a manifold that further includes a second chamber as described below
in reference to FIGS. 3 and 4.
[0017] The port 18 through the first plate 1 may be the same size on the first and second
faces 11 and 12, or the size may increase or decrease between the first and second
faces. In some embodiments, the size of the port is larger on the second face 12 of
the first plate 1. For example, on the first face 11, the port may be offset from
the center of the first plate 1, while on the second face 12, the port may be larger
and include the center (i.e., the geometric center).
[0018] As illustrated in FIG. 1B, the first
chamber comprises non-linear pathways (e.g., tortuous pathways) that connect the hollow,
electrically-conductive nozzles to a gas supply or vacuum source. In some embodiments,
including the embodiment illustrated in FIG. 1B, the first plurality of pathways 14,
is configured such that each pathway between one nozzle of the multiple hollow, electrically-conductive
nozzles 10 and the supply of plasma-generating gas or vacuum source (not shown) is
substantially the same in gas flow path volume. The phrase "substantially the same
in gas flow path volume" means that individual pathways 14 may differ in volume by
up to 10 (in some embodiments, up to 8, 6, 5, 2, or 1) percent. In some embodiments,
each pathway between one nozzle of the multiple hollow, electrically-conductive nozzles
10 and the supply of plasma-generating gas or vacuum source (not shown) is substantially
the same (in some embodiments, within 10, 8, 6, 5, 2, or 1 percent) in diameter. In
some embodiments, each pathway between one nozzle of the multiple hollow, electrically-conductive
nozzles 10 and the supply of plasma-generating gas or vacuum source (not shown) is
substantially the same (in some embodiments, within 10, 8, 6, 5, 2, or 1 percent)
in length. In the illustrated embodiment, a supply of plasma-generating gas or vacuum
source is accessible through channel 15. The first plurality of pathways 14 is configured
such that each pathway between one nozzle of the multiple hollow, electrically-conductive
nozzles 10 and channel 15 is substantially the same in both gas flow path volume and
length. This configuration is accomplished by use of the H patterns shown in FIG.
1B. In some embodiments, the depth and width of channel 15 are greater than or equal
to the depths and widths of the sides (i.e., arms) of the H patterns.
[0019] An exemplary hollow, electrically-conductive nozzle 10, useful as a component of
an apparatus disclosed herein, is shown FIG. 2. The illustrated nozzle may be useful,
for example, as a component of apparatus 9 or 90, shown in FIGS. 1A, 1B, and 4. The
size of the nozzle 10 may be selected based on the size of the container to be treated.
Prescription MDIs typically include canisters with openings having diameters of about
20 mm although the apparatus and method disclosed herein are not limited to treating
containers of this size.
[0020] The illustrated nozzle 10 has an inner diameter (ID) and an outer diameter (OD).
The outer diameter (OD) of the nozzle 10 should be such that the nozzle 10 will fit
into the container to be treated. For example, the outer diameter (OD) of nozzle 10
may be at least 0.125, 0.15, 0.175, 0.20, 0.225, 0.25 or 0.26 inches (3.2, 3.8, 4.4,
5.1, 5.7, 6.35 or 6.6 mm) and may be up to 0.31, 0.32, 0.35, 0.375, 0.4, 0.425, 0.45,
0.475, or 0.5 inches (7.9, 8.1, 8.9, 9.5, 10.2, 10.8, 11.4, 12.1, or 12.7 mm). In
some embodiments, the outer diameter is in a range from 0.125 to 0.5 inches (3.2 mm
to 12.7 mm), 0.225 to 0.375 inches (5.7 mm to 9.5 mm), or 0.25 to 0.35 inches (6.35
mm to 8.9 mm). In some embodiments, the inner diameter (ID) of nozzle 10 may be at
least 0.0625, 0.08, 0.10, 0.125, 0.15, 0.175, 0.20, 0.235, or 0.24 inches (1.6, 2.0,
2.5, 3.2, 3.8, 4.4, 5.1, 6.0, or 6.1 mm) and may be up to 0.28, 0.30, 0.32, 0.35,
0.4, 0.425, 0.45, 0.475, or 0.48 inches (7.1, 7.6, 8.1, 8.9, 10.2, 10.8, 11.4, 12.1,
or 12.2 mm). In some embodiments, the inner diameter is in a range from 0.0625 to
0.48 inches (1.6 mm to 12.2 mm), 0.125 to 0.35 inches (3.2 mm to 8.9 mm), or 0.2 to
0.32 inches (5.1 mm to 8.1 mm). The inner diameter may be selected based on the thickness
of the material used to make the nozzles. However, if the inner diameter is less than
0.0625 inches (1.6 mm), depending on the penetration of the nozzle into the container,
the bottom of the container may be treated excessively in comparison to other interior
portions of the container, which may result in non-uniform plasma treatment. In some
embodiments, the ratio of the outer diameter (OD) to the inner diameter (ID) is in
a range from 8:1 to 1.04:1, 5:1 to 1.1:1, or 3:1 to 1.5:1.
[0021] FIGS. 3A and 3B illustrate an electrically insulating block 8 that can be coupled
to the first plate 1 shown in FIGS. 1A and 1B to provide another exemplary embodiment
of a useful manifold for the apparatus according to the present disclosure. In the
illustrated embodiment of FIG. 3B, the first face 21 of insulating block 8 has a plurality
of interconnected pathways 24. The first face 21 of the insulating block 8 is disposed
on (e.g., joined or sealed to) the second face 12 of the first plate 1, so that the
second plurality of interconnected pathways 24 is in communication with port 18 in
first plate 1. The second plurality of interconnected pathways 24 extend to discrete
openings 26 in a second face 22 of insulating block 8 (shown in FIG. 3A). The multiple
hollow, electrically-conductive nozzles 10 pass through insulating block 8 and extend
out of the discrete openings 26 in the second face 22 of insulating block 8.
[0022] In some embodiments, including the embodiment illustrated in FIG. 3B, the second
chamber in the manifold comprises a second plurality of interconnected pathways, which
may be non-linear pathways (e.g., tortuous pathways). In the embodiment illustrated
in FIG. 3B, the second plurality of interconnected pathways 24 is configured such
that each pathway between one of the discrete openings 26 and the port 18 in the first
plate 1 has substantially the same volume and length. This configuration can be accomplished
by use of the H patterns shown in FIG. 3B. The phrase "substantially the same in volume"
means that individual pathways 24 may differ in volume by up to 10 (in some embodiments,
up to 8, 6, 5, 2, or 1) percent. In some embodiments, each pathway between one nozzle
of the multiple hollow, electrically-conductive nozzles 10 and port 18 is substantially
the same (in some embodiments, within 10, 8, 6, 5, 2, or 1 percent) in diameter. The
phrase "substantially the same in length" means that individual pathways 24 between
one nozzle of the multiple hollow, electrically-conductive nozzles 10 and port 18
is may differ in length by up to 10 (in some embodiments, up to 8, 6, 5, 2, or 1)
percent.
[0023] FIG. 4 illustrates an exploded view of an exemplary apparatus 90 according to the
present disclosure, which apparatus 90 includes a manifold 2 that comprises the first
plate 1 and multiple nozzles 10 shown in FIGS. 1A and 1B and insulating block 8 shown
in FIGS. 3A and 3B. Apparatus 90 further comprises base 5 that is disposed on (e.g.,
joined or sealed to) the first face 11 of first plate 1. The base 5 can be connected
to the first face 11 of the first plate 1 optionally using bolts 55 or other fasteners.
Similarly, the first face 21 of electrically insulating block 8 can be connected to
the second face 12 of the first plate 1 optionally using bolts 55 or other fasteners.
Base 5 has two connectors 54 and 58, one for attachment to a high pressure gas supply
and one for attachment to a vacuum source. Connector 54 is aligned with channel 15
leading to the first plurality of pathways 14. The base 5 and first plurality of pathways
14 in the first face 11 of the first plate 1 together define the first chamber of
manifold 2. The first chamber can optionally be sealed, for example, using an o-ring
in slot 17. Connector 58 is aligned with port 18 that extends through first plate
1 and is in communication with second plurality of interconnected pathways 24 in insulating
block 8. The second plurality of interconnected pathways 24 and second face 12 of
the first plate 1 together define the second chamber of manifold 2, which can optionally
be sealed, for example, using an o-ring in slot 27.
[0024] Apparatus 90 further comprises second plate 3 comprising slots 36 for multiple containers
30. Slots 36 are aligned with the discrete openings 26 in the second face of the insulating
block 8, shown in FIG. 3A. Second plate 3 also has a connection 35 for a radio frequency
(RF) power source so that RF power can be supplied to the multiple containers 30.
[0025] Referring again to FIG. 3A, discrete openings 26 each may have a sealing means (e.g.,
o-ring) to connect to one of the multiple containers 30, or the insulating base 8
may comprise a material that allows for a sealing connection when the multiple containers
30 are pressed into the discrete openings 26. In some embodiments, discrete openings
26 each also have a metal washer (not shown) that reinforces the opening. The metal
washer is made from a material (e.g., stainless steel) that provides a strong surface
on which each container can be sealed. Without wishing to be bound by theory, it is
also believed that the metal washer can also enhance the electric field near the opening
of the container to help enhance the coating near the opening. The presence of the
metal washer can also reduce the arcing that can occur at the brim of the container
30, and any arcing that may occur can arc to the metal washer, thereby preventing
damage to the container 30.
[0026] For plasma treatment methods according to the present disclosure in connection with
the embodiment illustrated in FIG. 4, 16 containers can be lowered onto insulating
block 8 so that the brim of each container is in contact with the second face 22 of
the insulating block 8 and so that a seal is created between each container at the
discrete opening 26. In this configuration, the 16 nozzles 10 extend into the 16 containers
30. Voltage can be applied to the containers and the nozzles grounded to create the
plasma and an ion sheath within the interior of the container, in order to treat the
interior of the containers. In some embodiments, to provide a gas flow through the
containers, the containers can be continuously evacuated via the second plurality
of interconnected pathways 24 while gas is supplied into the containers through nozzles
10. In other embodiments, the containers can be continuously evacuated via the nozzles
10 while gas is supplied into the containers from port 18 through second plurality
of interconnected pathways 24.
[0027] In some embodiments, methods according to the present disclosure comprise controlling
the temperature of at least one of the multiple hollow, electrically-conductive nozzles
or the multiple electrically-conductive containers while generating plasma. Controlling
the temperature can be carried out, for example, by passing a coolant through the
flow paths described below in reference to FIGS. 4 and 5. The coolant may be a gas
(e.g., air) or a liquid (e.g., water). The temperature during plasma generation can
advantageously be maintained below the melting point of the material used to make
the nozzles or containers but above the dew point so that condensation does not occur
on the nozzles or containers.
[0028] In the embodiment illustrated in FIG. 4, apparatus 90 further comprises top base
7, which is typically made from an insulating material. In some embodiments, when
top base 7 and second plate 3 are joined together, for example, using screws 55, they
together define an interior pocket (not shown) through which coolant can pass to cool
the second plate 3 and the multiple containers 30 during plasma treatment. Coolant
may flow into coolant entrance port 34 and out of coolant exit port 32 or the direction
of flow may be reversed. The second plate 3 can include flow paths for coolant (not
shown) extending between the coolant entrance port 34 and the coolant exit port 32.
These flow paths may surround the impressions made by slots 36 in the second plate
3.
[0029] Cooling first plate 1 during plasma treatment may also be useful. In the embodiment
illustrated in FIG. 4, first plate 1 comprises a coolant entrance port 42 and a coolant
exit port 44 with flow paths for coolant extending between the coolant entrance port
and the coolant exit port. Exemplary flow paths 48 are shown in FIG. 5. The flow paths
48 can be formed to extend through the first plate 1, and caps 49 can be used to close
the openings around the perimeter of the first plate 1. In the illustrated embodiment,
flow paths 48 are configured to pass between the multiple openings 16 for receiving
the multiple hollow, electrically-conductive nozzles 10 in the first plate 1. In this
configuration, coolant that is passed through the flow paths can cool both first plate
1 and nozzles 10.
[0030] Controlling the temperature of at least one of the multiple hollow, electrically-conductive
nozzles or the multiple electrically-conductive containers while generating plasma
can also be accomplished using methods external to the apparatus. For example, the
containers can be fan-cooled during plasma generation. Controlling the temperature
of the nozzles is typically advantageous for plasma etching and may also be advantageous
during plasma deposition.
[0031] A cross-sectional side view of a portion of another exemplary apparatus for plasma
treating multiple containers is shown in FIG. 6. The apparatus includes a manifold
102 having two generally horizontal first and second chambers 114 and 128, respectively.
In some examples, chamber 114 is connected to a gas feed/supply system, and chamber
128 is connected to a vacuum source. In some examples, chamber 128 is connected to
a gas feed/supply system, and chamber 114 is connected to a vacuum source. The manifold
includes vertical passages with appropriate seal systems 117 (e.g., o-rings) to allow
for sealing-connection to nozzles 110. The apparatus also includes insulating block
108 having discrete vertical openings 126 extending from a first face to a second
face and fitted below the manifold so that the discrete openings are aligned with
the vertical passages. The insulating block also has appropriate seal systems 118
(e.g., o-rings) for sealing to manifold 102.
[0032] In the example illustrated in FIGS. 6 and 7, the apparatus includes hollow, electrically-conductive
nozzles 110, each of which comprises a middle portion 161 and two extensions 163 on
opposite ends of the middle portion 161. The nozzle includes a central bore 165 and
outer bores 167 substantially parallel to the central bore, wherein the central bore
165 runs through the extensions and the middle portion, and the outer bores 167 run
through the middle portion 161. One end of each nozzle 110 is inserted through the
insulating block 108 into the manifold 102 so that the respective opening of the central
bore 165 taps into chamber 114 and the respective openings of the outer bores 167
tap into chamber 128. One extension 163 of nozzle 110 seals one of the outlet openings
of chamber 114. The middle portion 161 of each nozzle 110 seals one of the passages
from chamber 128 and is also sealed within the insulating block 108. The nozzle 110
can be screwed into manifold 102 using the illustrated threads. The openings of the
outer bores 167 are substantially flush with the lower surface of the insulating block
108, and the central bore 165 extends beyond the lower surface of the insulating block
108. In the example illustrated in FIG. 6, a sealing system119 is provided on the
lower side of insulating block 108 near the block/nozzle conjunction to allow for
a sealing-connection to the container to be treated.
[0033] For hollow, electrically-conductive nozzle 110 illustrated in FIG. 7, the middle
portion 161 has four outer bores 167 surrounding the central bore 165; however, only
three outer bores 167 are visible in the perspective view. In other examples, 2, 3,
5, 6, or more outer bores 167 surround the central bore 165. Typically, the outer
bores 167 are evenly distributed around the central bore 165. The extensions 163 including
central bore 165 of hollow, electrically-conductive nozzle 110 may have any of the
inner diameters, outer diameters, and ratios of outer diameter to inner diameter described
above for hollow, electrically-conductive nozzle 10. The inner diameter of the outer
bores 167 should be large enough to allow introduction or exhaustion of gas to or
from the container to be treated. In some embodiments, the inner diameter of outer
bores 167 is in a range from 0.03125 to 0.25 inches (0.8 mm to 6.35 mm), 0.047 to
0.125 inches (1.2 mm to 3.2 mm), or 0.05 to 0.1 inches (1.3 mm to 2.5 mm).
[0034] FIG. 8 illustrates a perspective view of exemplary apparatus 900 according to the
present disclosure, which apparatus 900 includes manifold 102, insulating block 108,
and multiple nozzles 110 as shown in cross-section in FIG. 6. Apparatus 900 further
comprises second plate 103 comprising slots 136 for multiple containers (not shown).
Slots 136 are aligned with the discrete openings 126 in the second face of the insulating
block 108, shown in FIG. 6. Second plate 103 also has a connection for a radio frequency
power source (not shown) so that RF power can be supplied to the multiple containers.
In the illustrated embodiment, second plate 103 is disposed on a second insulating
block 107 that is in turn disposed on a grounded base 105.
[0035] For plasma treatment methods according to the present disclosure in connection with
the example illustrated in FIG. 8, the four nozzles 110 can be lowered into four
containers so that the upper edge of the brim of each container is in contact with
the lower side of the middle portion 161 of nozzle 110 and so that a seal is created
between each container (outer surface of brim) and the outer lower surface of the
insulating block 108. Voltage can be applied to the containers and the nozzles grounded
to create the plasma and an ion sheath within the interior of the container, in order
to treat the interior of the containers. To provide a gas flow through the containers,
the containers can be continuously evacuated via the outer bores 167 (inlet openings
near the brim) while gas is supplied into the containers via the central bore 165,
or vice versa.
[0036] For the example illustrated in FIG. 8, at least one of the insulating block 108 or
second insulating block 107 can be provided with a coolant entrance port and a coolant
exit port with flow paths for coolant extending between the entrance port and the
exit port as described above for the embodiment illustrated in FIGS. 4 and 5. The
flow paths for coolant may provide a means for cooling at least one of the nozzles
or the containers during plasma treatment. Apparatus 900 can also be cooled by external
means (e.g., fans).
[0037] Various materials may be useful for constructing exemplary apparatuses illustrated
in FIGS. 1 to 8. Base 5; first plate 1; second plate 3, 103; and manifold 102 are
typically made from electrically-conductive materials (e.g., metals such as aluminum,
copper, and stainless steel). Insulating block 8, 108; top base 7; and second insulating
block 107 are typically made from electrically insulating materials, for example,
plastics (e.g., polytetrafluoroethylene, polyetheretherketone, polyetherketone, and
polyetherimide) and ceramics. In some embodiments, electrically insulating materials
useful for making insulating portions of the apparatus disclosed herein are made from
polyetherimide, (available under the trademark "ULTEM" (grade 1000) of General Electric
Company and available from many suppliers worldwide).
[0038] Various materials (e.g., aluminum, stainless steel, copper, or graphite) may be useful
for making the hollow, electrically-conductive nozzles 10, 110 useful for practicing
the present disclosure. In some embodiments, the nozzles are made from aluminum or
an aluminum alloy. Aluminum is a useful material in part because of its low sputter
yield, which means that it provides very little contamination on surfaces to be plasma
treated.
[0039] In some embodiments, the hollow, electrically-conductive nozzles 10, 110 are provided
with a surface dielectric coating, which may protect against etching and improve durability.
In some embodiments, the hollow, electrically-conductive nozzles 10, 110 are provided
with surface anodization. Anodizing is beneficial in hardening, for example, the aluminum
or aluminum alloy as well as removing or minimizing surface imperfections resulting
from fabrication (such as deep drawing) and facilitating the naturally occurring oxide
process, all of which facilitate overall durability of the nozzle. The anodization
can be carried out to a depth of up to 0.002 or 0.0015 inches (0.05 mm or 0.038 mm),
in some embodiments, a depth of at least 0.0005 or 0.001 inches (0.013 mm or 0.025
mm). The anodization may a total thickness of up to 0.004 inches (0.10 mm) (in some
embodiments, up to 0.003, 0.002, or 0.001 inches (0.076 mm, 0.05 mm, or 0.025 mm)).
Conveniently, for the embodiment illustrated in FIGS. 1A and 1B, anodization can be
carried out after the nozzles are connected to (e.g., pressed into) first plate 1.
[0040] In some embodiments, including those illustrated in Figs. 1A, 1B, 4, 5 or examples
including those illustrated in figures 6 and 8, the multiple outlet openings (16,
126) and the multiple hollow, electrically-conductive nozzles 10, 110 are arranged
in a corresponding, regular pattern. In other words, the multiple outlet openings
may be an array of outlet openings that is connected to an array of hollow, electrically-conductive
nozzles 10, 110. The array may be linear or two dimensional. The array of nozzles
10 may be useful for uniformly plasma treating an array of containers, for example,
by enabling uniform pressures among the containers in the array, described in further
detail below.
[0041] For the apparatus and method according to the present disclosure, the hollow, electrically-conductive
nozzles 10, 110 protrude from manifold 2, 102, as illustrated in FIGS. 1A, 1B, 4,
6, and 8. For the embodiments shown in FIGS. 1A and 1B, nozzles 10 protrude from first
plate 1. For the embodiment shown in FIG. 4 and examples shown in FIGS. 6, and 8,
nozzles 10, 110 protrude from insulating block 8, 108. The hollow, electrically nozzles
10, 110 protrude from the manifold in an apparatus disclosed herein so that they are
able to extend into the interiors of multiple containers.
[0042] The length of the nozzles and the portion that protrudes from the manifold can be
adjusted depending on the size of the container to be treated. Each container has
a distance between a brim and a bottom. For prescription MDI containers, this distance
can be 2.33 inches (5.9 cm), 1.275 inches (3.2 cm), or 1.22 inches (3.1 cm) or in
a range from 1.2 inches to 2.5 inches (3.0 cm to 6.35 cm). However, the apparatus
and method disclosed herein are not limited to treating containers of this size. In
some embodiments the hollow, electrically-conductive nozzles penetrate into the containers
in a range from 30 percent to 99 percent of the distance between the brim and the
bottom. The percent penetration may be calculated as the distance between the container
brim and tip of the nozzle divided by the distance between the brim and the bottom
of the container, with the quotient multiplied by 100. In some embodiments, the hollow,
electrically-conductive nozzles penetrate into the containers at least 30, 35, 40,
45, or 50 percent up to 95, 96, 97, 98, or 99 percent. Enhanced gas flow and plasma
generation may result when the nozzles penetrate into the containers in a range from
30 percent to 99 percent, which may enhance the uniformity of the plasma treatment
within a container. Furthermore, the distance between a tip of the nozzle and the
bottom of the container may, in some embodiments, be in a range from 0.0625 inches
(1.6 mm) up to 1.5 inches (38 mm), depending on the size of the container.
[0043] Various modifications of the illustrated apparatus of FIGS. 1A through 8 are envisioned.
For example, a nozzle 10 as shown in FIG. 2 can be useful in the apparatus shown in
FIGS. 6 and 8. With such a substitution, the lower portion of manifold 102 and insulating
block 108 can be modified such that there is a space (e.g., an unsealed space or physical
gap) surrounding the nozzle allowing communication between chamber 128 and a container
attached at opening 126. The space can be achieved, for example, by making the openings
126 in the insulating block 108 and the lower portion of manifold 102 larger in circumference
than the nozzles and eliminating the seals around the nozzles in these areas. Furthermore,
the apparatus of FIG. 8 can be modified to have a two-dimensional array instead of
the illustrated linear array, and the apparatus of FIG. 4 can be modified to have
a linear array instead of the illustrated two-dimensional array. The illustrated apparatuses
can also be modified to have any number of hollow, electrically-conductive nozzles,
as described above.
[0044] Furthermore, other hollow, electrically-conductive nozzles may be useful in the apparatus
and method according to the present disclosure. For example, the hollow, electrically-conductive
nozzle for at least one of delivering or exhausting plasma-generating gas may be a
partial electrode that has a coaxially disposed solid electrode, for example, through
its center. In some embodiments, the coaxially disposed solid electrode may penetrate
further into the container than the hollow nozzle portion. In other embodiments, the
bottom of the coaxially disposed solid electrode may be flush with the bottom of the
hollow nozzle portion. Or the coaxially disposed solid electrode may be shorter than
the hollow nozzle portion.
[0045] For the apparatuses 90, 900 shown in FIGS. 4 and 8, individual containers 30 (not
shown in FIG. 8) serve as the powered electrode. Therefore, for FIG. 4, 16 individual
plasma generators are formed when each of the nozzles 10 is grounded and each of the
containers 30 is powered. Similarly, in FIG. 8, four individual plasma generators
are formed. In embodiments wherein an individual container serves as a powered electrode,
the container typically has a sealing connection (e.g., using an o-ring or other seal
material) to the manifold around an individual hollow, electrically-conductive nozzle.
In embodiments wherein the individual containers serve as electrodes, the containers
can be made, for example, of aluminum, an aluminum alloy, or stainless steel, and
the interior surface of the containers may be anodized or formed with another dielectric
coating as described above. Typically the hollow, electrically-conductive nozzles
are centrally disposed in the electrically-conductive containers. Centrally disposed
typically means that a hollow, electrically-conductive nozzle occupies a space including
the geometric center of the container. In some embodiments, centrally disposed refers
to the hollow, electrically-conductive nozzle and the electrically-conductive container
being coaxial.
[0046] It is also envisioned that the apparatus according to the present disclosure may
be useful, for example, as a portion of a parallel plate plasma generator. Accordingly,
in some embodiments, the apparatus according to the present disclosure further comprises
an evacuable chamber joined to the manifold, wherein the multiple hollow, electrically-conductive
nozzles extends into the evacuable chamber, and an electrically-conductive plate within
the evacuable chamber in proximity to the multiple hollow, electrically-conductive
nozzles, wherein the conductive plate comprises a connection for a radio frequency
power source. A configuration similar to that described in International Pat. App.
Pub. No.
WO 2009/061895 (Jinks et al) and schematically illustrated in FIG. 6 of that reference may be useful. For example,
the containers may be placed inside a chamber on an RF powered electrode plate that
is isolated from the chamber by an insulating block. In operation, the electrically-conductive
plate can hold multiple containers to be treated, and the hollow, electrically-conductive
nozzles can be lowered into the containers typically without forming a seal between
the manifold and the containers. RF power can be applied to the conductive plate,
and the nozzles can be grounded during plasma generation. In some of these examples,
a modification of the apparatus shown in FIGS. 6 and 8 may be useful. For example,
the manifold 102 may be modified to have only one chamber, and a nozzle 10 such as
that shown in FIG. 2 may be used. Furthermore, an apparatus 9 shown in FIGS. 1A and
1B can be disposed on a vacuum chamber so that the nozzles extend into the chamber.
For these embodiments, the containers may be made from aluminum, an aluminum alloy,
or stainless steel as described above, and they can also be made, for example, from
glass, plastic (e.g. polyethylene terephthalate, polycarbonate, polyethylene, high
density polyethylene and polypropylene) and ceramics.
[0047] In the method according to the present disclosure, an RF electric field is applied
to the powered electrode (e.g., either the container or a plate electrode on which
the containers are placed), ionizing the gas and establishing a plasma. In the RF-generated
plasma, energy is coupled into the plasma through electrons. The plasma acts as the
charge carrier between the electrodes. In some embodiments, the plasma may be visible
as a colored cloud. The plasma is also generally thought to form an ion sheath proximate
at least to the RF-powered electrode. The ion sheath may appear as a darker area near
the RF-powered electrode. The depth of the ion sheath normally ranges from about 1
mm to about 50 mm and depends on factors such as the type and concentration of gas
used, pressure, the spacing between the electrodes, and relative size of the electrodes.
For example, reduced pressures will increase the size of the ion sheath. When the
electrodes are different sizes, a larger, stronger ion sheath will form around the
smaller electrode. Generally, the larger the difference in electrode size, the larger
the difference in the size of the ion sheaths, and increasing the voltage across the
ion sheath will increase ion bombardment energy.
[0048] Plasma, created from the gas within the container, can be powered by an RF generator
(e.g., available from Seren IPS, Inc., Vineland, New Jersey, Model No. R1001,) operating
at a frequency in a range, for example, from 0.001 to 100 MHz). The RF generator (e.g.,
an oscillator) can provide power at a typical frequency in a range from 0.01 to 50
MHz, for example, 13.56 MHz or any whole number (e.g., 1, 2, or 3) multiple thereof.
The power source may be connected to the apparatus (e.g., at connection 35) via a
network that serves to match the impedance of the power supply with that of the transmission
line to effectively transmit RF power through a coaxial transmission line. Such matching
networks are commercially available (e.g., from Advanced Energy, Fort Collins, CO,
as Rf Plasma Products Model AMN-10).
[0049] As described above, the apparatus and method according to the present disclosure
are useful for a variety of plasma treatment processes. For the application of medicinal
inhalation devices, the apparatus and method disclosed herein may be useful, for example,
for plasma priming and plasma deposition of a non-metal coating on the inside of a
container.
[0050] In some embodiments, the plasma treatment method according to the present disclosure
includes plasma priming (e.g., by oxygen or argon plasma). For example, the method
includes treating the interior surface of a container with oxygen plasma under conditions
of ion bombardment. Typically for plasma priming, power densities in the range from
about 0.10 to about 0.95 watts/square cm can be applied. Also, typically for plasma
priming, flow densities of the priming gas in the range from about 0.01 to about 1
sccm/square cm, in some embodiments 0.05 to 1 about sccm/square cm, and in some embodiments,
about 0.1 to about 0.6 sccm/square cm can be applied. Power density is a ratio of
the plasma power (typically in watts) and the surface area (typically in square cm)
of the substrate to be treated (i.e. the density of plasma power at or upon the surface
to-be-coated). Similarly flow density is a ratio of the flow (typically in standard
cubic centimeters per minute (sccm)) of the gas and the surface area of the substrate
to be treated. Before plasma priming, the interior surfaces of the containers can
be solvent washed (e.g., with an organic solvent such as acetone or ethanol).
[0051] In some embodiments, the plasma treatment method according to the present disclosure
includes depositing diamond-like glass on the interior surface of the container. Diamond-like
glass coatings are coatings comprising carbon, silicon, hydrogen, and oxygen typically
provided by plasma deposition under conditions of ion bombardment. In these embodiments,
a gas comprising one or more organosilicon compounds is introduced into the system
at a flow rate selected so that a sufficient flow is provided to establish a suitable
pressure at which to carry out plasma deposition. In some embodiments, the pressure
at the interior surface of the container is at least 100 millitorr (13.3 Pa) or 300
millitorr (40 Pa), and in some embodiments is in the range from 500 millitorr to 5000
millitorr (66.7 Pa to 667 Pa). In some embodiments, the flow density of the organosilicon
compound applied is at least about 0.01 sccm/square cm, in some embodiments at least
about 0.05 sccm/square cm, and in some embodiments at least about 0.1 sccm/square
cm. Flow densities are typically up to about 0.30 sccm/square cm, in some embodiments
up to about 0.25 sccm/square cm. These flow densities typically refer to organosilicon
compounds only (i.e., without any non-organosilicon assist gases). The organosilicon
compound may be a mixture of organosilicon compounds. These pressures and flow densities
may be advantageous in providing superior coating densities as well as uniform and
conformal coatings having a high degree of flexibility and resistance to cracking.
Favorably the plasma density is greater than about 0.10 watts/square cm. It has been
found advantageous in facilitating the provision of flexible coatings, to apply lower
power density in combination with longer deposition times.
[0052] For plasma deposition of diamond-like glass, typically elemental silicon present
in the at least one organosilicon compound is present in an amount of at least about
5 atomic percent of the gas mixture. In some embodiments, the organosilicon compound
comprises at least one of trimethylsilane, triethylsilane, trimethoxysilane, triethoxysilane,
tetramethylsilane, tetraethylsilane, tetramethoxysilane, tetraethoxysilane, hexamethylcyclotrisiloxane,
tetramethylcyclotetrasiloxane, tetraethylcyclotetrasiloxane, octamethylcyclotetrasiloxane,
hexamethyldisiloxane, or bistrimethylsilylmethane. In some embodiments of the plasma
treatment method disclosed herein, providing a gas inside the containers to be treated
comprises providing at least one of tetramethylsilane or tetraethyoxysilane (in some
embodiments, tetramethylsilane).
[0053] In some embodiments of the plasma treatment method according to the present disclosure,
the gas provided to the interiors of the containers (i.e., the source gas) includes
an organosilicon compound and may further comprise an additional gas or gases. Each
additional gas can be added separately or in combination with each other. If a gas
is mixed along with the organosilicon compound(s), the atomic percent of silicon in
the gas mixture generally is calculated based on the volumetric (or molar) flow rates
of the component gases in the mixture. The source gas may, for example, further comprise
at least one of argon or hydrogen. Argon normally is not incorporated into the deposited
coating but enhances ion bombardment, while hydrogen may promote the formation of
high packing density while providing an additional source of hydrogen in the deposited
composition. Optionally the source gas may further comprise at least one of ammonia
or nitrogen. However, in some embodiments, the plasma-deposited diamond-like glass
coating is substantially free of nitrogen (e.g. at most about 5 atomic percent of
nitrogen (on a hydrogen free basis)), in some embodiments free of nitrogen. The source
gas may further comprise oxygen gas. In these embodiments, the amount of oxygen gas
is less than 35% on a molar basis, in particular less than 30% on a molar basis.
[0054] In some embodiments, the plasma treatment method according to the present disclosure
comprises depositing an oxygen-lean diamond-like glass coating on the interior surfaces
of the containers. In these embodiments, the organosilicon compound may be free of
oxygen atoms, and the source gas may be free of oxygen gas. In the event the source
gas comprises oxygen gas and/or an organosilicon compound including oxygen atoms,
in some embodiments, the atomic ratio of oxygen (O) to silicon (Si) (O : Si) in the
source gas up to 3 : 1, in some embodiments, up to 2.5 : 1, in some embodiments up
to 1 : 1, an in some embodiments, up to 0.8 : 1. In some embodiments, the amount of
oxygen assist gas or oxygen-containing organosilicon(s) is no more than that corresponding
to 5% on an atomic basis of oxygen relative to total content of silicon on an atomic
basis.
[0055] Plasma deposition of a diamond-like glass coating typically occurs at a rate ranging
from about 1 to about 100 nm/second. The rate will depend on conditions including,
for example, pressure, power, concentration of gas, types of gases, and relative size
of the electrodes. In general, the deposition rate increases with increasing power,
pressure, and concentration of gas, although the rate can approach an upper limit.
In some embodiments, plasma deposition is carried out for a period of time such that
the deposited diamond-like glass coating has a thickness in the range from about 5
nm to about 5000 nm. In some embodiments, the thickness of the diamond-like glass
coating is at least 100 nm, 250 nm, or 550 nm. In some embodiments, the thickness
of the diamond-like glass coating is up to 5000 nm, 3500 nm, 2500 nm, or up to 2000
nm.
[0057] In some embodiments, the plasma treatment method according to the present disclosure
includes plasma etching (i.e., plasma cleaning). In some embodiments, a plasma etching
step is useful, for example, for removing a thin film layer deposited on the plasma
apparatus, particularly the nozzle electrodes, in a prior step. The gas that is used
to generate an etching plasma typically includes oxygen gas and a fluorocarbon (e.g.,
CF
4, C
2F
6, or C
3F
8). The molar concentration of fluorocarbon gas in the mixture is typically 0 to 60%
depending upon the particular type of fluorocarbon and on the composition of the deposited
layer to be cleaned. More fluorocarbon percentage is needed if the fluorine:carbon
ratio of the fluorocarbon is lower or if the silicon content of the deposited layer
is higher. Argon can also be a useful gas for plasma etching in combination with at
least one of oxygen or a fluorocarbon. Typically for plasma etching, power densities
in the range from about 0.1 to about 1 watt/square cm can be applied. Also, typically
for plasma priming, flow densities of the priming gas in the range from about 0.1
to about 1 sccm/square cm can be applied. Plasma etching or cleaning can also remove
oils, other organic or silicon containing residual layers, and other contaminants
from the containers and from the hollow, electrically-conductive electrodes. In some
embodiments of the method disclosed herein, plasma etching is integrated with plasma
priming and plasma deposition. For example, plasma etching or cleaning can be used
to remove a coating (e.g., diamond like glass or plasma polymer) from the nozzles
and to clean the interior surface of the container. What is removed from the nozzle
and container surfaces can be exhausted through the nozzles or through the physical
gap surrounding the nozzles, depending on the particular embodiment of the apparatus
used. Oxygen gas can then be provided inside the container under the conditions of
plasma priming. In some embodiments, an oxide layer is reformed on the container interior
during plasma priming. Finally, a depositing plasma can be generated, for example,
using source gas containing an organosilicon compound to provide a diamond like glass
coating. Advantageously, in the apparatus disclosed herein, plasma etching, plasma
priming, and plasma deposition can all be carried out on at least a portion of the
interior surface of multiple containers without removing the containers from the apparatus
between plasma processes.
[0058] In some embodiments, the plasma treatment method according to the present disclosure
comprises depositing a fluoropolymer on at least a portion of the interior surfaces
of the containers. In some embodiments, pure monomer plasma is used, by which is meant
that the gaseous atmosphere in which the plasma is struck and maintained consists
entirely of the monomer or monomers. In some embodiments, the gaseous atmosphere includes
one or more diluent gases. Exemplary useful monomers to form a fluoropolymer include
CF
4, C
2F
6, C
3F
6, C
4F
8, CF
3CHFCF
3, CF
3CH
2F, C
5F
10H
2, C
6F
12, C
6F
14, and C
8F
18. These monomers may be used singly, to form a homopolymer, or as part of a blend
of monomers to produce a co-polymer. Exemplary useful blends of monomers include CF
4/C
4F
8, CF
4/C
2H
4, CF
4/CH
4, CF
4/C
2H
6, C
4F
8/CH
4, C
4F
8/C
2H
6, CF
4/CF
3CHFCF
3 and/or CF
3CH
2F, C
4F
8/CF
3CHFCF
3 and/or CF
3CH
2F.
[0059] Other types of plasma polymers can be deposited using the apparatus and method according
to the present disclosure. Examples of these plasma polymers include plasma polymerized
organosilicons, silazanes, hydrocarbons, acrylates, glycols, and organometallics,
and exemplary plasma polymers may include other functional groups from gases such
as ammonia, nitrogen, sulfur dioxide, and hydrogen peroxide.
[0060] Although it was proposed in International Pat. Appl. Pub. No.
WO 2008/146025 (Stevenson et al.) that a can to be plasma treated can act as an RF electrode, the configuration of
electrodes, gas inlet, and exhaust outlet described in that publication would appear
to result in uneven gas flow in the can and consequently provide an uneven plasma
treatment within the can. The present disclosure provides an apparatus that can have
an electrode coaxial with the gas inlet and exhaust pathways, thereby allowing more
uniform gas flow, which would result in more uniform plasma treatment of a container
in the method according to the present disclosure.
[0061] Furthermore, the present disclosure provides a remarkably effective way for plasma
treating multiple containers simultaneously. The apparatus and method disclosed can
be usefully scaled to a large number (e.g., greater than 1000) of containers. The
apparatus according to the present disclosure is readily modifiable to achieve substantially
uniform pressures among the multiple containers to be treated. In some embodiments
of the apparatus and method disclosed herein, there is a pressure difference among
the multiple containers of up to ten (in some embodiments, up to 9, 8, 5, 4, 3, 2,
or 1) percent. The difference in pressure among multiple containers can be minimized
in some embodiments by minimizing the cross-sectional area of the gas inlet and exhaust
flow paths relative to the cross-sectional area of the manifold. Also, in the embodiment
illustrated in FIGS. 1A, 1B, 3 and 4, the difference in pressure among multiple containers
is minimized by incorporating substantially equal flow paths into and out of each
container, regardless of container position.
[0062] The invention is defined by the claims. The following selected embodiments of the
disclosure do not form part of the invention.
Selected Embodiments of the Disclosure
[0063] In a first embodiment, the present disclosure provides an apparatus for plasma treating
multiple containers, the apparatus comprising:
a manifold comprising a first chamber with multiple outlet openings; and
multiple hollow, electrically-conductive nozzles for at least one of delivering or
exhausting plasma-generating gas, wherein the multiple hollow, electrically-conductive
nozzles are connected to the multiple outlet openings and protrude from the manifold.
[0064] In a second embodiment, the present disclosure provides the apparatus according to
the first embodiment, wherein each of the hollow, electrically-conductive nozzles
has an inner diameter in a range from 1.6 millimeters to 12.2 millimeters.
[0065] In a third embodiment, the present disclosure provides the apparatus according to
the first or second embodiment, wherein each of the hollow, electrically-conductive
nozzles has an inner diameter and an outer diameter, and wherein the ratio of the
outer diameter to the inner diameter is in a range from 8:1 to 1.04:1.
[0066] In a fourth embodiment, the present disclosure provides the apparatus according to
any one of the first to third embodiments, wherein each of the hollow, electrically-conductive
nozzles has a surface dielectric coating. In some of these embodiments, each of the
hollow, electrically-conductive nozzles has an anodized surface.
[0067] In a fifth embodiment, the present disclosure provides the apparatus according to
any one of the first to fourth embodiments, wherein the first chamber comprises non-linear
pathways between the hollow, electrically-conductive nozzles and at least one of a
supply of plasma-generating gas or a vacuum source.
[0068] In a sixth embodiment, the present disclosure provides the apparatus according to
any one of the first to fifth embodiments, wherein the first chamber comprises tortuous
pathways between the hollow, electrically-conductive nozzles and at least one of a
supply of plasma-generating gas or a vacuum source.
[0069] In a seventh embodiment, the present disclosure provides the apparatus according
to any one of the first to sixth embodiments, wherein the manifold comprises a first
plate having a first face and a second face, wherein the first chamber comprises a
first plurality of interconnected pathways in the first face of the first plate for
connecting the multiple hollow, electrically-conductive nozzles to a supply of plasma-generating
gas or a vacuum source, and wherein the multiple hollow, electrically-conductive nozzles
protrude from the second face of the first plate.
[0070] In an eighth embodiment, the present disclosure provides the apparatus according
to the seventh embodiment, wherein the first plurality of pathways are configured
such that each pathway between one of the hollow, electrically-conductive nozzles
and the supply of plasma-generating gas or the vacuum source is substantially the
same in volume.
[0071] In a ninth embodiment, the present disclosure provides the apparatus according to
the seventh or eighth embodiment, wherein the first plurality of pathways are configured
such that each pathway between one of the hollow, electrically-conductive nozzles
and the supply of plasma-generating gas or the vacuum source is substantially the
same in length.
[0072] In a tenth embodiment, the present disclosure provides the apparatus according to
any one of the first to ninth embodiments, wherein the manifold further comprises
a second chamber adjacent the first chamber, the second chamber comprising multiple
passages therethrough aligned with the multiple outlet openings, wherein the multiple
hollow, electrically-conductive nozzles extend through the multiple passages.
[0073] In an eleventh embodiment, the present disclosure provides the apparatus according
to the tenth embodiment, wherein each of the multiple passages in the second chamber
comprises a space surrounding one of the hollow, electrically-conductive nozzles.
[0074] In a twelfth embodiment, the present disclosure provides the apparatus according
to the tenth or eleventh embodiments, wherein the second chamber comprises non-linear
(e.g., tortuous) interconnected pathways.
[0075] In a thirteenth embodiment, the present disclosure provides the apparatus according
to any one of the seventh to ninth embodiments, wherein the manifold further comprises
a second chamber comprising a second plurality of interconnected pathways in a first
face of an insulating block, the first face of the insulating block disposed on the
second face of the first plate, wherein the first plate further comprises a port extending
therethrough, wherein the second plurality of interconnected pathways is in communication
with the port in the first plate and each of the second plurality of interconnected
pathways extends to discrete openings in a second face of the insulating block, and
wherein the multiple hollow, electrically-conductive nozzles protrude from the discrete
openings in the second face.
[0076] In a fourteenth embodiment, the present disclosure provides the apparatus according
to the thirteenth embodiment, wherein the second plurality of interconnected pathways
is configured such that each pathway between one of the discrete openings and the
port in the first plate has substantially the same volume.
[0077] In a fifteenth embodiment, the present disclosure provides the apparatus according
to any one of the first to fourth embodiments, further comprising:
a second chamber having passages therethrough aligned with the multiple outlet openings
in the first chamber; and
an insulating block having discrete openings extending from a first face to a second
face of the insulating block and aligned with the multiple outlet openings in the
first chamber,
wherein each of the hollow, electrically-conductive nozzles comprises a middle portion
and two extensions on opposite ends of the middle portion, a central bore extending
through the two extensions and the middle portion, and at least two outer bores substantially
parallel to the central bore extending through only the middle portion, wherein the
central bore taps into the first chamber, wherein the at least two outer bores tap
into the second chamber, and wherein the multiple hollow, electrically-conductive
nozzles protrude from the second face of the insulating block through the discrete
openings.
[0078] In a sixteenth embodiment, the present disclosure provides an apparatus for plasma
treatment of multiple containers, the apparatus comprising:
a manifold comprising:
a first chamber having multiple outlet openings;
a second chamber disposed adjacent the first chamber and having multiple passages
therethrough aligned with the multiple outlet openings in the first chamber, wherein
one of the first or second chambers is adapted to connect to a gas supply, and one
of the first or second chambers is adapted to connect to a vacuum source; and
an insulating block disposed adjacent the second chamber such that the second chamber
is interposed between the first chamber and a first face of the insulating block,
the insulating block having discrete openings extending from the first face to a second
face of the insulating block and aligned with the multiple outlet openings in the
first chamber;
multiple hollow, electrically-conductive nozzles inserted through the discrete openings
in the insulating block, through the multiple passages through the second chamber,
and into the first chamber through the multiple outlet openings, each nozzle comprising:
a middle portion and two extensions on opposite ends of the middle portion;
a central bore extending through the two extensions and the middle portion; and
at least two outer bores substantially parallel to the central bore and extending
through only the middle portion,
wherein the central bore taps into the first chamber and seals one of the multiple
outlet openings, wherein the middle portion is sealed within one of the discrete openings
in the insulating block, wherein the at least two outer bores tap into the second
chamber, wherein the discrete opening in the second face of insulating block comprises
a sealing system for receiving a container to be treated, and wherein one of the extensions
protrudes from the discrete opening in the second face of the insulating block.
[0079] In a seventeenth embodiment, the present disclosure provides an apparatus for plasma
treatment of multiple containers, the apparatus comprising:
multiple hollow, electrically-conductive nozzles for at least one of delivering or
exhausting plasma-generating gas; and
a manifold comprising:
a first chamber in a first plate, wherein the first chamber comprises a first plurality
of interconnected pathways in the first plate for connecting the multiple hollow,
electrically-conductive nozzles to a supply of plasma-generating gas or a vacuum source;
and
a second chamber comprising a second plurality of interconnected pathways in a first
face of an insulating block, the first face of the insulating block disposed next
to the first plate, wherein the first plate further comprises a port extending therethrough,
wherein the second plurality of interconnected pathways is in communication with the
port in the first plate and each of the second plurality of interconnected pathways
extends to discrete openings in a second face of the insulating block, wherein the
multiple hollow, electrically-conductive nozzles protrude from the discrete openings
in the second face, and wherein each discrete opening in the second face of insulating
block comprises a sealing system for receiving a container to be treated.
[0080] In an eighteenth embodiment, the present disclosure provides the apparatus according
to any one of the thirteenth to seventeenth embodiments, further comprising a second
plate comprising:
slots for multiple containers, the slots aligned with the discrete openings in the
second face of the insulating block; and
a connection for a radio frequency power source.
[0081] In a nineteenth embodiment, the present disclosure provides the apparatus according
to the eighteenth embodiment, wherein the second plate further comprises a coolant
entrance port and a coolant exit port with flow paths for coolant extending between
the coolant entrance port and the coolant exit port.
[0082] In a twentieth embodiment, the present disclosure provides the apparatus according
to any one of the first to nineteenth embodiments, wherein the manifold further comprises
a coolant entrance port and a coolant exit port with flow paths for coolant extending
between the coolant entrance port and the coolant exit port.
[0083] In a twenty-first embodiment, the present disclosure provides the apparatus according
to any one of the first to ninth embodiments, further comprising:
an evacuable chamber connected to the manifold, wherein the multiple hollow, electrically-conductive
nozzles extend into the evacuable chamber; and
a conductive plate within the evacuable chamber in proximity to the multiple hollow,
electrically-conductive nozzles, wherein the conductive plate comprises a connection
for a radio frequency power source.
[0084] In a twenty-second embodiment, the present disclosure provides a method of plasma
treating multiple electrically-conductive containers, the method comprising:
providing a reactor system comprising an apparatus according to any one of the first
to twentieth embodiments;
inserting the multiple hollow, electrically-conductive nozzles into the multiple electrically-conductive
containers;
grounding the multiple hollow, electrically-conductive nozzles while applying radio
frequency power to the multiple electrically-conductive containers;
evacuating the multiple electrically-conductive containers;
providing a gas inside the multiple electrically-conductive containers; and
generating a plasma to treat an interior surface of the multiple electrically-conductive
containers;
wherein at least one of evacuating or providing the gas is carried out through the
hollow, electrically-conductive nozzles.
[0085] In a twenty-third embodiment, the present disclosure provides the method according
to the twenty-second embodiment, wherein providing the gas is carried out through
the hollow, electrically-conductive nozzles.
[0086] In a twenty-fourth embodiment, the present disclosure provides the method according
to the twenty-second or twenty-third embodiment, wherein the hollow, electrically-conductive
nozzles are centrally disposed in (e.g., coaxial with) the electrically-conductive
containers.
[0087] In a twenty-fifth embodiment, the present disclosure provides the method according
to any one of the twenty-second to twenty-fourth embodiments, wherein there is a pressure
difference among the multiple electrically-conductive containers of up to ten percent.
[0088] In a twenty-sixth embodiment, the present disclosure provides the method according
to any one of the twenty-second to twenty-fifth embodiments, wherein each of the electrically-conductive
containers has a distance between a brim and a bottom, and wherein the hollow, electrically-conductive
nozzles penetrate into the electrically-conductive containers in a range from 30 percent
to 99 percent of the distance.
[0089] In a twenty-seventh embodiment, the present disclosure provides the method according
to any one of the twenty-second to twenty-sixth embodiments, wherein a distance between
a tip of one of the multiple hollow, electrically-conductive nozzles and a bottom
of one of the multiple electrically-conductive containers in a range from 1.6 mm to
38.1 mm.
[0090] In a twenty-eighth embodiment, the present disclosure provides the method according
to any one of the twenty-second to twenty-seventh embodiments, wherein exhaust gas
from each of the electrically-conductive containers is vented through pathways having
the substantially the same volume.
[0091] In a twenty-ninth embodiment, the present disclosure provides the method according
to any one of the twenty-second to twenty-eighth embodiments, further comprising controlling
the temperature of at least one of the multiple hollow, electrically-conductive nozzles
or the multiple electrically-conductive containers while generating the plasma.
[0092] In a thirtieth embodiment, the present disclosure provides the method according to
any one of the twenty-second to twenty-ninth embodiments, further comprising depositing
diamond like glass on the interior surface of the electrically-conductive containers.
[0093] In a thirty-first embodiment, the present disclosure provides the method according
to any one of the twenty-second to twenty-ninth embodiments, further comprising depositing
a fluoropolymer on the interior surface of the electrically-conductive containers.
[0094] In a thirty-second embodiment, the present disclosure provides the method according
to any one of the twenty-second to twenty-ninth embodiments, further comprising depositing
a plasma polymer on the interior surface of the electrically-conductive containers.
[0095] In a thirty-third embodiment, the present disclosure provides the method according
to any one of the twenty-second to thirty-second embodiments, wherein generating a
plasma comprises generating an etching plasma.
[0096] In a thirty-fourth embodiment, the present disclosure provides the method according
to any one of the twenty-second to thirty-second embodiments, wherein generating a
plasma comprises generating a priming plasma.
[0097] In a thirty-fifth embodiment, the present disclosure provides a method of plasma
treating multiple electrically-conductive containers, the method comprising:
providing a reactor system comprising an apparatus according to the twenty-first embodiment;
inserting the multiple hollow, electrically-conductive nozzles into the multiple electrically-conductive
containers;
grounding the multiple hollow, electrically-conductive nozzles while applying radio
frequency power to the multiple electrically-conductive containers;
evacuating the multiple electrically-conductive containers;
providing a gas inside the conductive plate; and
generating a plasma to treat an interior surface of the multiple electrically-conductive
containers;
wherein at least one of evacuating or providing the gas is carried out through the
hollow, electrically-conductive nozzles.
[0098] Objects and advantages of this disclosure are further illustrated by the following
examples, but the particular materials and amounts thereof recited in these examples,
as well as other conditions and details, should not be construed to unduly limit this
disclosure.
EXAMPLES
[0099] Examples 1 and 2 were conducted to measure the pressure variability for a plurality
of containers in different embodiments of the apparatus according to the present disclosure.
Example 1
[0100] An MDI canister (aluminum, 19 mL brimful capacity available from 3M Healthcare, Clitheroe
UK) was modified so that it was connected to a monometer obtained from MKS Instruments,
Andover, MA, under the trade designation "BARATRON". Using an expanded and modified
version of the apparatus in FIG. 8, the modified canister was inserted over one of
the nozzles 10 (nozzle dimensions: 0.259 inch (6.6 mm) OD x 0.237 inch (6.0 mm) ID)
in a linear 1x22 manifold. The outer surface of the brim of the canister was secured
to the corresponding opening in the insulating block by means of an o-ring seal. There
was a physical gap surrounding the nozzle formed by the opening in the insulating
block and the lower portion of the vacuum chamber. Canisters that had not been modified
were similarly secured at each of the remaining 21 positions in the manifold. After
the system was fully assembled, vacuum was applied and the baseline pressure was measured.
Tetramethyl silane (TMS) gas was then introduced at a total flow rate of 100 sccm
(nominally 4.5 sccm/can) and the pressure was measured once a steady state was obtained.
The pressure difference was determined by subtracting the baseline pressure from the
pressure following TMS introduction. The procedure was repeated to obtain measurements
at each of the 22 canister positions in the apparatus. The average pressure difference
measured at the canister positions in the apparatus was 873 mTorr (116 Pa). The maximum
variability in pressure difference measured between canister positions in the apparatus
was 66.4 mTorr (8.85 Pa).
Example 2
[0101] An MDI canister (aluminum, 19 mL brimful capacity available from 3M Healthcare, Clitheroe
UK) was modified so that it was connected to a monometer obtained from MKS Instruments
under the trade designation "BARATRON". Using the apparatus in FIG. 4, the modified
canister was inserted over one of the nozzles (nozzle dimensions: 0.259 inch (6.6
mm) OD x 0.237 inch (6.0 mm) ID) in the 4x4 manifold. The outer surface of the brim
of the canister was secured to the corresponding opening in the insulating block by
means of an o-ring seal. Canisters that had not been modified were similarly secured
to each of the remaining 15 positions in the manifold. After the system was fully
assembled, vacuum was applied and the baseline pressure was measured. Tetramethyl
silane (TMS) gas was then introduced at a total flow rate of 100 sccm (nominally 6.3
sccm/can) and the pressure was measured once a steady state was obtained. The pressure
difference was determined by subtracting the baseline pressure from the pressure following
TMS introduction. The procedure was repeated to obtain measurements at each of the
16 canister positions in the apparatus. The average pressure difference measured at
the canister positions in the apparatus was 844 mTorr (112.5 Pa). The maximum variability
in pressure difference measured between canister positions in the apparatus was 7.9
mTorr (1.05 Pa).